An organic polymer having a silicon-containing group that has a hydroxy group or hydrolyzable group bonded to a silicon atom and that can be crosslinked by forming a siloxane bond (hereinafter, also referred to as “crosslinkable silicon group”) has been known to have properties by which the organic polymer can be formed into a liquid form for easy coating or charging and by which a rubber-like cured product can be obtained by crosslinking caused by formation of a siloxane bond involved with a hydrolysis reaction or the like of the crosslinkable silicon group as a result of actions of moisture in the air or the like even at room temperature. Because of this, this polymer is widely used for applications in sealing materials, adhesive agents, coating materials, and the like. Examples of the polymer having a crosslinkable silicon group include polyoxyalkylene polymers and (meth)acrylate-based polymers.
Adhering process using an adhesive agent is generally performed by, after coating the adhesive agent on a first adherend, bonding a second adherend to the first adherend. At this time, if curing proceeds at the time of coating the adhesive agent to the first adherend, the second adherend cannot be bonded. Such a problem often occurs in a case where an adhesive agent with a high cure rate is used and/or in a case where, even when an adhesive agent with a cure rate that is not high is used, a coated area of the adhesive agent is large or a coated thickness of the adhesive agent is small. Because of this, if curing can proceed at the time of adding some sort of trigger, such as photoirradiation, sufficient time can be allocated for the coating operation (elongating usable life), and thus workability during the adhering process can be enhanced. Long usable life may be required not only for an adhesive agent but also for a coating material or sealing material.
Patent Document 1 discloses a curable composition comprising: an organic polymer having a crosslinkable silicon group, and a compound that generates an acid or base when irradiated with light. The compound that generates an acid or base when irradiated with light does not act as a curing catalyst before the light irradiation but generates the acid or base that serves as the curing catalyst after the light irradiation. Therefore, the composition remains as a liquid since curing does not proceed even when water is present prior to the light irradiation, and the curing can proceed utilizing the light irradiation as a trigger. Accordingly, the curable composition disclosed in Patent Document 1 can be suitably used for adhesive agents or the like required to have a long usable life.
Although the organic polymer having a crosslinkable silicon group is used for sealing materials, adhesive agents, coating materials, and the like as described above, adhesive properties with respect to an adherend (substrate) is necessary in this case. As a method of improving adhesive properties of the organic polymer having a crosslinkable silicon group, use of a silane coupling agent, such as aminosilane, epoxysilane, mercaptosilane, isocyanate silane, or phenylsilane, has been known. However, the aminosilane cannot be used in the curable composition comprising: an organic polymer having a crosslinkable silicon group, and a compound that generates an acid or base when irradiated with light disclosed in Patent Document 1. This is because the curing proceeds before the light irradiation since the aminosilane is a base itself. Therefore, when a silane coupling agent is used to improve the adhesive properties, a neutral silane coupling agent, such as epoxysilane or phenylsilane, has to be used; however, when such a compound is used, sufficient adhesive properties may not be obtained.